Calendar listing fails with _CalendarAPI missing principal attribute

[ldehner]

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Steps to reproduce

1. Use an integration or client that calls the calendar listing functionality.
2. Trigger the action to list all existing calendars.
3. Observe that the request fails instead of returning available calendars.

Expected behaviour

The system should return a list of calendars accessible to the current user.

Actual behaviour

The calendar listing request fails with an internal error instead of returning calendars.

Error observed:

AttributeError("'_CalendarAPI' object has no attribute 'principal'")
No calendar list is returned.

[context_agent] Error: Error: Traceback (most recent call last):
  File "/ex_app/lib/main.py", line 180, in handle_task
    output = await react(task, nextcloud)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/ex_app/lib/agent.py", line 179, in react
    async for event in graph.astream(new_input, thread, stream_mode="values"):
  File "/root/.cache/pypoetry/virtualenvs/context-agent-il7asoJj-py3.11/lib/python3.11/site-packages/langgraph/pregel/main.py", line 3000, in astream
    async for _ in runner.atick(
  File "/root/.cache/pypoetry/virtualenvs/context-agent-il7asoJj-py3.11/lib/python3.11/site-packages/langgraph/pregel/_runner.py", line 304, in atick
    await arun_with_retry(
  File "/root/.cache/pypoetry/virtualenvs/context-agent-il7asoJj-py3.11/lib/python3.11/site-packages/langgraph/pregel/_retry.py", line 137, in arun_with_retry
    return await task.proc.ainvoke(task.input, config)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/root/.cache/pypoetry/virtualenvs/context-agent-il7asoJj-py3.11/lib/python3.11/site-packages/langgraph/_internal/_runnable.py", line 705, in ainvoke
    input = await asyncio.create_task(
            ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/root/.cache/pypoetry/virtualenvs/context-agent-il7asoJj-py3.11/lib/python3.11/site-packages/langgraph/_internal/_runnable.py", line 473, in ainvoke
    ret = await self.afunc(*args, **kwargs)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/ex_app/lib/agent.py", line 146, in call_model
    response = await bound_model.ainvoke([system_prompt] + state["messages"], config)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/root/.cache/pypoetry/virtualenvs/context-agent-il7asoJj-py3.11/lib/python3.11/site-packages/langchain_core/language_models/chat_models.py", line 417, in ainvoke
    llm_result = await self.agenerate_prompt(
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/root/.cache/pypoetry/virtualenvs/context-agent-il7asoJj-py3.11/lib/python3.11/site-packages/langchain_core/language_models/chat_models.py", line 1036, in agenerate_prompt
    return await self.agenerate(
           ^^^^^^^^^^^^^^^^^^^^^
  File "/root/.cache/pypoetry/virtualenvs/context-agent-il7asoJj-py3.11/lib/python3.11/site-packages/langchain_core/language_models/chat_models.py", line 994, in agenerate
    raise exceptions[0]
  File "/root/.cache/pypoetry/virtualenvs/context-agent-il7asoJj-py3.11/lib/python3.11/site-packages/langchain_core/language_models/chat_models.py", line 1164, in _agenerate_with_cache
    result = await self._agenerate(
             ^^^^^^^^^^^^^^^^^^^^^^
  File "/ex_app/lib/nc_model.py", line 152, in _agenerate
    raise Exception("Nextcloud TaskProcessing Task failed")
Exception: Nextcloud TaskProcessing Task failed
During task with name 'agent' and id 'b8c5a4c1-7eb8-9083-0753-6b7c8ab12a86'

	POST /ocs/v1.php/apps/app_api/api/v1/log?format=json
	from 127.0.0.1 by -- at Mar 21, 2026 at 3:50:26 AM

Server configuration

Web server: Apache/Nginx

Database: MySQL/Maria/SQLite/PostgreSQL

PHP version: 8.2/8.3/8.4

Nextcloud version: (see Nextcloud admin page)

List of activated apps

 - activity: 6.0.0-dev.0
  - admin_audit: 1.23.0
  - app_api: 33.0.0
  - assistant: 3.3.0
  - bruteforcesettings: 6.0.0-dev.0
  - calendar: 6.2.1
  - circles: 33.0.0
  - cloud_federation_api: 1.17.0
  - comments: 1.23.0
  - contacts: 8.4.1
  - contactsinteraction: 1.14.1
  - dashboard: 7.13.0
  - dav: 1.36.0
  - deck: 1.17.0
  - drawio: 4.2.3
  - federatedfilesharing: 1.23.0
  - federation: 1.23.0
  - files: 2.5.0
  - files_downloadlimit: 5.1.0-dev.0
  - files_external: 1.25.1
  - files_pdfviewer: 6.0.0-dev.0
  - files_reminders: 1.6.0
  - files_sharing: 1.25.2
  - files_trashbin: 1.23.0
  - files_versions: 1.26.0
  - firstrunwizard: 6.0.0-dev.0
  - integration_openai: 4.3.0
  - logreader: 6.0.0
  - lookup_server_connector: 1.21.0
  - mail: 5.7.4
  - nextcloud-aio: 0.8.0
  - nextcloud_announcements: 5.0.0
  - notes: 4.13.1
  - notifications: 6.0.0
  - notify_push: 1.3.1
  - oauth2: 1.21.0
  - password_policy: 5.0.0-dev.0
  - photos: 6.0.0-dev.0
  - privacy: 5.0.0-dev.0
  - profile: 1.2.0
  - provisioning_api: 1.23.0
  - recommendations: 6.0.0-dev.0
  - related_resources: 4.0.0-dev.0
  - richdocuments: 10.1.2
  - serverinfo: 5.0.0-dev.0
  - settings: 1.16.0
  - sharebymail: 1.23.0
  - support: 5.0.0
  - survey_client: 5.0.0-dev.0
  - systemtags: 1.23.0
  - tasks: 0.17.1
  - text: 7.0.0-dev.3
  - theming: 2.8.0
  - twofactor_backupcodes: 1.22.0
  - twofactor_totp: 15.0.0-dev.0
  - updatenotification: 1.23.0
  - user_oidc: 8.6.1
  - user_status: 1.13.0
  - viewer: 6.0.0-dev.0
  - weather_status: 1.13.0
  - webhook_listeners: 1.5.0
  - workflowengine: 2.15.0
  
ExApps:
  - context_agent (Nextcloud Context Agent): 2.5.1 [enabled]

Nextcloud configuration

{
    "system": {
        "one-click-instance": true,
        "one-click-instance.user-limit": 100,
        "memcache.local": "\\OC\\Memcache\\APCu",
        "apps_paths": [
            {
                "path": "\/var\/www\/html\/apps",
                "url": "\/apps",
                "writable": false
            },
            {
                "path": "\/var\/www\/html\/custom_apps",
                "url": "\/custom_apps",
                "writable": true
            }
        ],
        "check_data_directory_permissions": false,
        "memcache.distributed": "\\OC\\Memcache\\Redis",
        "memcache.locking": "\\OC\\Memcache\\Redis",
        "redis": {
            "host": "***REMOVED SENSITIVE VALUE***",
            "password": "***REMOVED SENSITIVE VALUE***",
            "port": 6379
        },
        "overwritehost": "cloud.abc.app",
        "overwriteprotocol": "https",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "localhost",
            "cloud.abc.app"
        ],
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "pgsql",
        "version": "33.0.1.0",
        "overwrite.cli.url": "https:\/\/cloud.abc.app\/",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbport": "",
        "dbtableprefix": "oc_",
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "installed": true,
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "maintenance": false,
        "updatechecker": true,
        "loglevel": 2,
        "log_type": "file",
        "logfile": "\/var\/www\/html\/data\/nextcloud.log",
        "log_rotate_size": 10485760,
        "log.condition": {
            "apps": [
                "admin_audit"
            ]
        },
        "preview_max_x": 2048,
        "preview_max_y": 2048,
        "jpeg_quality": 60,
        "enabledPreviewProviders": {
            "1": "OC\\Preview\\Image",
            "2": "OC\\Preview\\MarkDown",
            "3": "OC\\Preview\\MP3",
            "4": "OC\\Preview\\TXT",
            "5": "OC\\Preview\\OpenDocument",
            "6": "OC\\Preview\\Movie",
            "7": "OC\\Preview\\Krita",
            "0": "OC\\Preview\\Imaginary",
            "23": "OC\\Preview\\ImaginaryPDF"
        },
        "enable_previews": true,
        "upgrade.disable-web": true,
        "mail_smtpmode": "smtp",
        "trashbin_retention_obligation": "auto, 30",
        "versions_retention_obligation": "auto, 30",
        "activity_expire_days": 30,
        "simpleSignUpLink.shown": false,
        "share_folder": "\/Shared",
        "one-click-instance.link": "https:\/\/nextcloud.com\/all-in-one\/",
        "upgrade.cli-upgrade-link": "https:\/\/github.com\/nextcloud\/all-in-one\/discussions\/2726",
        "updatedirectory": "\/nc-updater",
        "maintenance_window_start": 100,
        "allow_local_remote_servers": true,
        "davstorage.request_timeout": 3600,
        "documentation_url.server_logs": "https:\/\/github.com\/nextcloud\/all-in-one\/discussions\/5425",
        "htaccess.RewriteBase": "\/",
        "dbpersistent": false,
        "auth.bruteforce.protection.enabled": true,
        "ratelimit.protection.enabled": true,
        "files_external_allow_create_new_local": true,
        "default_phone_region": "AT",
        "trusted_proxies": "***REMOVED SENSITIVE VALUE***",
        "forwarded_for_headers": [
            "HTTP_X_FORWARDED_FOR",
            "HTTP_CF_CONNECTING_IP"
        ],
        "preview_imaginary_url": "***REMOVED SENSITIVE VALUE***",
        "preview_imaginary_key": "***REMOVED SENSITIVE VALUE***",
        "mail_sendmailmode": "smtp",
        "mail_smtphost": "***REMOVED SENSITIVE VALUE***",
        "mail_smtpport": "465",
        "mail_smtpname": "***REMOVED SENSITIVE VALUE***",
        "mail_smtppassword": "***REMOVED SENSITIVE VALUE***",
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "mail_smtptimeout": 30,
        "mail_smtpauth": true,
        "mail_smtpsecure": "ssl",
        "php_memory_limit": "3072M",
        "updater.release.channel": "stable",
        "app_install_overwrite": [
            "nextcloud-aio"
        ],
        "DOMAIN": "cloud.abc.app",
        "AIO_VERSION": "v12.8.0"
    }
}

Browser

Browser name: Safari

[marcelklehr]

Hi @ldehner
I cannot reproduce this with the latest code in the repository, so it seems to be fixed already. The next release will have the fix.